+ + int sf_command (SNDFILE *sndfile, int cmd, void *data, int datasize) ; ++
+ This function allows the caller to retrieve information from or change aspects of the + library behaviour. + Examples include retrieving a string containing the library version or changing the + scaling applied to floating point sample data during read and write. + Most of these operations are performed on a per-file basis. +
++ The cmd parameter is an integer identifier which is defined in <sndfile.h>. + All of the valid command identifiers have names beginning with "SFC_". + Data is passed to and returned from the library by use of a void pointer. + The library will not read or write more than datasize bytes from the void pointer. + For some calls no data is required in which case data should be NULL and datasize + may be used for some other purpose. +
++ The available commands are as follows: +
+ +| SFC_GET_LIB_VERSION | +Retrieve the version of the library. | +
| SFC_GET_LOG_INFO | +Retrieve the internal per-file operation log. | +
| SFC_CALC_SIGNAL_MAX | +Calculate the measured maximum signal value. | +
| SFC_CALC_NORM_SIGNAL_MAX | +Calculate the measured normalised maximum signal value. | +
| SFC_CALC_MAX_ALL_CHANNELS | +Calculate the peak value for each channel. | +
| SFC_CALC_NORM_MAX_ALL_CHANNELS | +Calculate the normalised peak for each channel. | +
| SFC_GET_SIGNAL_MAX | +Retrieve the peak value for the file (as stored in the file header). | +
| SFC_GET_MAX_ALL_CHANNELS | +Retrieve the peak value for each channel (as stored in the file header). | +
| SFC_SET_NORM_FLOAT | +Modify the normalisation behaviour of the floating point reading and writing functions. | +
| SFC_SET_NORM_DOUBLE | +Modify the normalisation behaviour of the double precision floating point reading and writing functions. | +
| SFC_GET_NORM_FLOAT | +Retrieve the current normalisation behaviour of the floating point reading and writing functions. | +
| SFC_GET_NORM_DOUBLE | +Retrieve the current normalisation behaviour of the double precision floating point reading and writing functions. | +
| SFC_SET_SCALE_FLOAT_INT_READ | +Set/clear the scale factor when integer (short/int) data is read from a file + containing floating point data. | +
| SFC_SET_SCALE_INT_FLOAT_WRITE | +Set/clear the scale factor when integer (short/int) data is written to a file + as floating point data. | +
| SFC_GET_SIMPLE_FORMAT_COUNT | +Retrieve the number of simple formats supported by libsndfile. | +
| SFC_GET_SIMPLE_FORMAT | +Retrieve information about a simple format. | +
| SFC_GET_FORMAT_INFO | +Retrieve information about a major or subtype format. | +
| SFC_GET_FORMAT_MAJOR_COUNT | +Retrieve the number of major formats. | +
| SFC_GET_FORMAT_MAJOR | +Retrieve information about a major format type. | +
| SFC_GET_FORMAT_SUBTYPE_COUNT | +Retrieve the number of subformats. | +
| SFC_GET_FORMAT_SUBTYPE | +Retrieve information about a subformat. | +
| SFC_SET_ADD_PEAK_CHUNK | +Switch the code for adding the PEAK chunk to WAV and AIFF files on or off. | +
| SFC_UPDATE_HEADER_NOW | +Used when a file is open for write, this command will update the file + header to reflect the data written so far. | +
| SFC_SET_UPDATE_HEADER_AUTO | +Used when a file is open for write, this command will cause the file header + to be updated after each write to the file. | +
| SFC_FILE_TRUNCATE | +Truncate a file open for write or for read/write. | +
| SFC_SET_RAW_START_OFFSET | +Change the data start offset for files opened up as SF_FORMAT_RAW. | +
| SFC_SET_CLIPPING | +Turn on/off automatic clipping when doing floating point to integer + conversion. | +
| SFC_GET_CLIPPING | +Retrieve current clipping setting. | +
| SFC_GET_EMBED_FILE_INFO | +Retrieve information about audio files embedded inside other files. | +
| SFC_GET_AMBISONIC | +Test a WAVEX file for Ambisonic format | +
| SFC_SET_AMBISONIC | +Modify a WAVEX header for Ambisonic format | +
| SFC_SET_VBR_ENCODING_QUALITY | +Set the the Variable Bit Rate encoding quality | +
| SFC_RAW_NEEDS_ENDSWAP | +Determine if raw data needs endswapping | +
| SFC_GET_BROADCAST_INFO | +Retrieve the Broadcast Chunk info | +
| SFC_SET_BROADCAST_INFO | +Set the Broadcast Chunk info | +
| SFC_GET_LOOP_INFO | +Get loop info | +
| SFC_GET_INSTRUMENT | +Get instrument info | +
| SFC_SET_INSTRUMENT | +Set instrument info | +
| SFC_SET_VBR_ENCODING_QUALITY | +Set variable bit rate encoding quality | +
+Retrieve the version of the library as a string. +
++Parameters: +
+ sndfile : Not used + cmd : SFC_GET_LIB_VERSION + data : A pointer to a char buffer + datasize : The size of the the buffer ++
+Example: +
++ char buffer [128] ; + sf_command (NULL, SFC_GET_LIB_VERSION, buffer, sizeof (buffer)) ; ++ +
+Retrieve the log buffer generated when opening a file as a string. This log +buffer can often contain a good reason for why libsndfile failed to open a +particular file. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_LOG_INFO + data : A pointer to a char buffer + datasize : The size of the the buffer ++
+Example: +
++ char buffer [2048] ; + sf_command (sndfile, SFC_GET_LOG_INFO, buffer, sizeof (buffer)) ; ++ +
+Retrieve the measured maximum signal value. This involves reading through +the whole file which can be slow on large files. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_CALC_SIGNAL_MAX + data : A pointer to a double + datasize : sizeof (double) ++
+Example: +
++ double max_val ; + sf_command (sndfile, SFC_CALC_SIGNAL_MAX, &max_val, sizeof (max_val)) ; ++ +
+Retrieve the measured normalised maximum signal value. This involves reading +through the whole file which can be slow on large files. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_CALC_NORM_SIGNAL_MAX + data : A pointer to a double + datasize : sizeof (double) ++
+Example: +
++ double max_val ; + sf_command (sndfile, SFC_CALC_NORM_SIGNAL_MAX, &max_val, sizeof (max_val)) ; ++ +
+Calculate the peak value (ie a single number) for each channel. +This involves reading through the whole file which can be slow on large files. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_CALC_MAX_ALL_CHANNELS + data : A pointer to a double + datasize : sizeof (double) * number_of_channels ++
+Example: +
++ double peaks [number_of_channels] ; + sf_command (sndfile, SFC_CALC_MAX_ALL_CHANNELS, peaks, sizeof (peaks)) ; ++
+Calculate the normalised peak for each channel. +This involves reading through the whole file which can be slow on large files. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_CALC_NORM_MAX_ALL_CHANNELS + data : A pointer to a double + datasize : sizeof (double) * number_of_channels ++
+Example: +
++ double peaks [number_of_channels] ; + sf_command (sndfile, SFC_CALC_NORM_MAX_ALL_CHANNELS, peaks, sizeof (peaks)) ; ++
+Retrieve the peak value for the file as stored in the file header. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_SIGNAL_MAX + data : A pointer to a double + datasize : sizeof (double) ++
+Example: +
++ double max_peak ; + sf_command (sndfile, SFC_GET_SIGNAL_MAX, &max_peak, sizeof (max_peak)) ; ++
+Retrieve the peak value for the file as stored in the file header. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_SIGNAL_MAX + data : A pointer to an array of doubles + datasize : sizeof (double) * number_of_channels ++
+Example: +
++ double peaks [number_of_channels] ; + sf_command (sndfile, SFC_GET_MAX_ALL_CHANNELS, peaks, sizeof (peaks)) ; ++
+This command only affects data read from or written to using the floating point functions: +
++ size_t sf_read_float (SNDFILE *sndfile, float *ptr, size_t items) ; + size_t sf_readf_float (SNDFILE *sndfile, float *ptr, size_t frames) ; + + size_t sf_write_float (SNDFILE *sndfile, float *ptr, size_t items) ; + size_t sf_writef_float (SNDFILE *sndfile, float *ptr, size_t frames) ; ++
+Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_NORM_FLOAT + data : NULL + datasize : SF_TRUE or SF_FALSE ++
+For read operations setting normalisation to SF_TRUE means that the data from all +subsequent reads will be be normalised to the range [-1.0, 1.0]. +
++For write operations, setting normalisation to SF_TRUE means than all data supplied +to the float write functions should be in the range [-1.0, 1.0] and will be scaled +for the file format as necessary. +
++For both cases, setting normalisation to SF_FALSE means that no scaling will take place. +
++Example: +
++ sf_command (sndfile, SFC_SET_NORM_FLOAT, NULL, SF_TRUE) ; + + sf_command (sndfile, SFC_SET_NORM_FLOAT, NULL, SF_FALSE) ; ++
+This command only affects data read from or written to using the double precision +floating point functions: +
++ size_t sf_read_double (SNDFILE *sndfile, double *ptr, size_t items) ; + size_t sf_readf_double (SNDFILE *sndfile, double *ptr, size_t frames) ; + + size_t sf_write_double (SNDFILE *sndfile, double *ptr, size_t items) ; + size_t sf_writef_double (SNDFILE *sndfile, double *ptr, size_t frames) ; ++
+Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_NORM_DOUBLE + data : NULL + datasize : SF_TRUE or SF_FALSE ++
+For read operations setting normalisation to SF_TRUE means that the data +from all subsequent reads will be be normalised to the range [-1.0, 1.0]. +
++For write operations, setting normalisation to SF_TRUE means than all data supplied +to the double write functions should be in the range [-1.0, 1.0] and will be scaled +for the file format as necessary. +
++For both cases, setting normalisation to SF_FALSE means that no scaling will take place. +
++Example: +
++ sf_command (sndfile, SFC_SET_NORM_DOUBLE, NULL, SF_TRUE) ; + + sf_command (sndfile, SFC_SET_NORM_DOUBLE, NULL, SF_FALSE) ; ++
+Retrieve the current float normalisation mode. +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_NORM_FLOAT + data : NULL + datasize : anything ++
+Example: +
++ normalisation = sf_command (sndfile, SFC_GET_NORM_FLOAT, NULL, 0) ; ++
+Retrieve the current float normalisation mode. +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_NORM_DOUBLE + data : NULL + datasize : anything ++
+Example: +
++ normalisation = sf_command (sndfile, SFC_GET_NORM_DOUBLE, NULL, 0) ; ++
+Set/clear the scale factor when integer (short/int) data is read from a file +containing floating point data. +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_SCALE_FLOAT_INT_READ + data : NULL + datasize : TRUE or FALSE ++
+Example: +
++ sf_command (sndfile, SFC_SET_SCALE_FLOAT_INT_READ, NULL, SF_TRUE) ; ++
+Set/clear the scale factor when integer (short/int) data is written to a file +as floating point data. +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_SCALE_FLOAT_INT_READ + data : NULL + datasize : TRUE or FALSE ++
+Example: +
++ sf_command (sndfile, SFC_SET_SCALE_INT_FLOAT_WRITE, NULL, SF_TRUE) ; ++
+Retrieve the number of simple formats supported by libsndfile. +
++Parameters: +
++ sndfile : Not used. + cmd : SFC_GET_SIMPLE_FORMAT_COUNT + data : a pointer to an int + datasize : sizeof (int) ++
+Example: +
++ int count ; + sf_command (sndfile, SFC_GET_SIMPLE_FORMAT_COUNT, &count, sizeof (int)) ; ++
+Retrieve information about a simple format. +
++Parameters: +
++ sndfile : Not used. + cmd : SFC_GET_SIMPLE_FORMAT + data : a pointer to an SF_FORMAT_INFO struct + datasize : sizeof (SF_FORMAT_INFO) ++
+The SF_FORMAT_INFO struct is defined in <sndfile.h> as: +
+
+ typedef struct
+ { int format ;
+ const char *name ;
+ const char *extension ;
+ } SF_FORMAT_INFO ;
+
++When sf_command() is called with SF_GET_SIMPLE_FORMAT, the value of the format +field should be the format number (ie 0 <= format <= count value obtained using +SF_GET_SIMPLE_FORMAT_COUNT). +
++Example: +
+
+ SF_FORMAT_INFO format_info ;
+ int k, count ;
+
+ sf_command (sndfile, SFC_GET_SIMPLE_FORMAT_COUNT, &count, sizeof (int)) ;
+
+ for (k = 0 ; k < count ; k++)
+ { format_info.format = k ;
+ sf_command (sndfile, SFC_GET_SIMPLE_FORMAT, &format_info, sizeof (format_info)) ;
+ printf ("%08x %s %s\n", format_info.format, format_info.name, format_info.extension) ;
+ } ;
+
++Retrieve information about a major or subtype format. +
++Parameters: +
++ sndfile : Not used. + cmd : SFC_GET_FORMAT_INFO + data : a pointer to an SF_FORMAT_INFO struct + datasize : sizeof (SF_FORMAT_INFO) ++
+The SF_FORMAT_INFO struct is defined in <sndfile.h> as: +
+
+ typedef struct
+ { int format ;
+ const char *name ;
+ const char *extension ;
+ } SF_FORMAT_INFO ;
+
++When sf_command() is called with SF_GET_FORMAT_INFO, the format field is +examined and if (format & SF_FORMAT_TYPEMASK) is a valid format then the struct +is filled in with information about the given major type. +If (format & SF_FORMAT_TYPEMASK) is FALSE and (format & SF_FORMAT_SUBMASK) is a +valid subtype format then the struct is filled in with information about the given +subtype. +
++Example: +
+
+ SF_FORMAT_INFO format_info ;
+
+ format_info.format = SF_FORMAT_WAV ;
+ sf_command (sndfile, SFC_GET_FORMAT_INFO, &format_info, sizeof (format_info)) ;
+ printf ("%08x %s %s\n", format_info.format, format_info.name, format_info.extension) ;
+
+ format_info.format = SF_FORMAT_ULAW ;
+ sf_command (sndfile, SFC_GET_FORMAT_INFO, &format_info, sizeof (format_info)) ;
+ printf ("%08x %s\n", format_info.format, format_info.name) ;
+
++Retrieve the number of major formats. +
++Parameters: +
++ sndfile : Not used. + cmd : SFC_GET_FORMAT_MAJOR_COUNT + data : a pointer to an int + datasize : sizeof (int) ++
+Example: +
++ int count ; + sf_command (sndfile, SFC_GET_FORMAT_MAJOR_COUNT, &count, sizeof (int)) ; ++
+Retrieve information about a major format type. +
++Parameters: +
++ sndfile : Not used. + cmd : SFC_GET_FORMAT_MAJOR + data : a pointer to an SF_FORMAT_INFO struct + datasize : sizeof (SF_FORMAT_INFO) ++
+Example: +
+
+ SF_FORMAT_INFO format_info ;
+ int k, count ;
+
+ sf_command (sndfile, SFC_GET_FORMAT_MAJOR_COUNT, &count, sizeof (int)) ;
+
+ for (k = 0 ; k < count ; k++)
+ { format_info.format = k ;
+ sf_command (sndfile, SFC_GET_FORMAT_MAJOR, &format_info, sizeof (format_info)) ;
+ printf ("%08x %s %s\n", format_info.format, format_info.name, format_info.extension) ;
+ } ;
+
++For a more comprehensive example, see the program list_formats.c in the examples/ +directory of the libsndfile source code distribution. +
++Retrieve the number of subformats. +
++Parameters: +
++ sndfile : Not used. + cmd : SFC_GET_FORMAT_SUBTYPE_COUNT + data : a pointer to an int + datasize : sizeof (int) ++
+Example: +
++ int count ; + sf_command (sndfile, SFC_GET_FORMAT_SUBTYPE_COUNT, &count, sizeof (int)) ; ++
+Enumerate the subtypes (this function does not translate a subtype into +a string describing that subtype). +A typical use case might be retrieving a string description of all subtypes +so that a dialog box can be filled in. +
++ +
++Parameters: +
++ sndfile : Not used. + cmd : SFC_GET_FORMAT_SUBTYPE + data : a pointer to an SF_FORMAT_INFO struct + datasize : sizeof (SF_FORMAT_INFO) ++
+Example 1: Retrieve all sybtypes supported by the WAV format. +
+
+ SF_FORMAT_INFO format_info ;
+ int k, count ;
+
+ sf_command (sndfile, SFC_GET_FORMAT_SUBTYPE_COUNT, &count, sizeof (int)) ;
+
+ for (k = 0 ; k < count ; k++)
+ { format_info.format = k ;
+ sf_command (sndfile, SFC_GET_FORMAT_SUBTYPE, &format_info, sizeof (format_info)) ;
+ if (! sf_format_check (format_info.format | SF_FORMAT_WAV))
+ continue ;
+ printf ("%08x %s\n", format_info.format, format_info.name) ;
+ } ;
+
++Example 2: Print a string describing the SF_FORMAT_PCM_16 subtype. +
+
+ SF_FORMAT_INFO format_info ;
+ int k, count ;
+
+ sf_command (sndfile, SFC_GET_FORMAT_SUBTYPE_COUNT, &count, sizeof (int)) ;
+
+ for (k = 0 ; k < count ; k++)
+ { format_info.format = k ;
+ sf_command (sndfile, SFC_GET_FORMAT_SUBTYPE, &format_info, sizeof (format_info)) ;
+ if (format_info.format == SF_FORMAT_PCM_16)
+ { printf ("%08x %s\n", format_info.format, format_info.name) ;
+ break ;
+ } ;
+ } ;
+
++For a more comprehensive example, see the program list_formats.c in the examples/ +directory of the libsndfile source code distribution. +
++By default, WAV and AIFF files which contain floating point data (subtype SF_FORMAT_FLOAT +or SF_FORMAT_DOUBLE) have a PEAK chunk. +By using this command, the addition of a PEAK chunk can be turned on or off. +
++Note : This call must be made before any data is written to the file. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_ADD_PEAK_CHUNK + data : Not used (should be NULL) + datasize : TRUE or FALSE. ++
+Example: +
++ /* Turn on the PEAK chunk. */ + sf_command (sndfile, SFC_SET_ADD_PEAK_CHUNK, NULL, SF_TRUE) ; + + /* Turn off the PEAK chunk. */ + sf_command (sndfile, SFC_SET_ADD_PEAK_CHUNK, NULL, SF_FALSE) ; ++
+The header of an audio file is normally written by libsndfile when the file is +closed using sf_close(). +
++There are however situations where large files are being generated and it would +be nice to have valid data in the header before the file is complete. +Using this command will update the file header to reflect the amount of data written +to the file so far. +Other programs opening the file for read (before any more data is written) will +then read a valid sound file header. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_UPDATE_HEADER_NOW + data : Not used (should be NULL) + datasize : Not used. ++
+Example: +
++ /* Update the header now. */ + sf_command (sndfile, SFC_UPDATE_HEADER_NOW, NULL, 0) ; ++
+Similar to SFC_UPDATE_HEADER_NOW but updates the header at the end of every call +to the sf_write* functions. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_UPDATE_HEADER_NOW + data : Not used (should be NULL) + datasize : SF_TRUE or SF_FALSE ++
+Example: +
++ /* Turn on auto header update. */ + sf_command (sndfile, SFC_SET_UPDATE_HEADER_AUTO, NULL, SF_TRUE) ; + + /* Turn off auto header update. */ + sf_command (sndfile, SFC_SET_UPDATE_HEADER_AUTO, NULL, SF_FALSE) ; ++
+Truncate a file that was opened for write or read/write. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_FILE_TRUNCATE + data : A pointer to an sf_count_t. + datasize : sizeof (sf_count_t) ++ +
+Truncate the file to the number of frames specified by the sf_count_t pointed +to by data. +After this command, both the read and the write pointer will be +at the new end of the file. +This command will fail (returning non-zero) if the requested truncate position +is beyond the end of the file. +
++Example: +
++ /* Truncate the file to a length of 20 frames. */ + sf_count_t frames = 20 ; + sf_command (sndfile, SFC_FILE_TRUNCATE, &frames, sizeof (frames)) ; ++
+Change the data start offset for files opened up as SF_FORMAT_RAW. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_RAW_START_OFFSET + data : A pointer to an sf_count_t. + datasize : sizeof (sf_count_t) ++ +
+For a file opened as format SF_FORMAT_RAW, set the data offset to the value +given by data. +
++Example: +
++ /* Reset the data offset to 5 bytes from the start of the file. */ + sf_count_t offset = 5 ; + sf_command (sndfile, SFC_SET_RAW_START_OFFSET, &offset, sizeof (offset)) ; ++
+Turn on/off automatic clipping when doing floating point to integer conversion. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_CLIPPING + data : NULL + datasize : SF_TRUE or SF_FALSE. ++ +
+Turn on (datasize == SF_TRUE) or off (datasize == SF_FALSE) clipping. +
++Example: +
++ sf_command (sndfile, SFC_SET_CLIPPING, NULL, SF_TRUE) ; ++
+Turn on/off automatic clipping when doing floating point to integer conversion. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_CLIPPING + data : NULL + datasize : 0 ++ +
+Retrieve the current cliiping setting. +
++Example: +
++ sf_command (sndfile, SFC_GET_CLIPPING, NULL, 0) ; ++
+Get the file offset and file length of a file enbedded within another +larger file. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_CLIPPING + data : a pointer to an SF_EMBED_FILE_INFO struct + datasize : sizeof (SF_EMBED_FILE_INFO) ++
+The SF_EMBED_FILE_INFO struct is defined in <sndfile.h> as: +
+
+ typedef struct
+ { sf_count_t offset ;
+ sf_count_t length ;
+ } SF_EMBED_FILE_INFO ;
+
++Test if the current file has the GUID of a WAVEX file for any of the Ambisonic +formats. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_WAVEX_GET_AMBISONIC + data : NULL + datasize : 0 ++
+ The Ambisonic WAVEX formats are defined here : + + http://dream.cs.bath.ac.uk/researchdev/wave-ex/bformat.html. +
++Set the GUID of a new WAVEX file to indicate an Ambisonics format. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_WAVEX_SET_AMBISONIC + data : NULL + datasize : SF_AMBISONIC_NONE or SF_AMBISONIC_B_FORMAT ++
+Turn on (SF_AMBISONIC_B_FORMAT) or off (SF_AMBISONIC_NONE) encoding. +This command is currently only supported for files with SF_FORMAT_WAVEX format. +
++ The Ambisonic WAVEX formats are defined here : + + http://dream.cs.bath.ac.uk/researchdev/wave-ex/bformat.html. +
++Set the the Variable Bit Rate encoding quality. +The encoding quality value should be between 0.0 (lowest quality) and 1.0 +(highest quality). +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_VBR_ENCODING_QUALITY + data : A pointer to a double value + datasize : sizeof (double) ++
+The command must be sent before any audio data is written to the file. +
++
++Determine if raw data read using + + sf_read_raw +needs to be end swapped on the host CPU. +
++For instance, will return SF_TRUE on when reading WAV containing +SF_FORMAT_PCM_16 data on a big endian machine and SF_FALSE on a little endian +machine. +
++Parameters: +
+ sndfile : A valid SNDFILE* pointer + cmd : SFC_RAW_NEEDS_ENDSWAP + data : NULL + datasize : 0 ++ +
+Retrieve the Broadcast Extension Chunk from WAV (and related) files. +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_BROADCAST_INFO + data : a pointer to an SF_BROADCAST_INFO struct + datasize : sizeof (SF_BROADCAST_INFO) ++
+The SF_BROADCAST_INFO struct is defined in <sndfile.h> as: +
+
+ typedef struct
+ { char description [256] ;
+ char originator [32] ;
+ char originator_reference [32] ;
+ char origination_date [10] ;
+ char origination_time [8] ;
+ unsigned int time_reference_low ;
+ unsigned int time_reference_high ;
+ short version ;
+ char umid [64] ;
+ char reserved [190] ;
+ unsigned int coding_history_size ;
+ char coding_history [256] ;
+ } SF_BROADCAST_INFO ;
+
+
++Set the Broadcast Extension Chunk for WAV (and related) files. +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_BROADCAST_INFO + data : a pointer to an SF_BROADCAST_INFO struct + datasize : sizeof (SF_BROADCAST_INFO) ++ +
+Retrieve loop information for file including time signature, length in +beats and original MIDI base note +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_LOOP_INFO + data : a pointer to an SF_LOOP_INFO struct + datasize : sizeof (SF_LOOP_INFO) ++
+The SF_BROADCAST_INFO struct is defined in <sndfile.h> as: +
+
+ typedef struct
+ { short time_sig_num ; /* any positive integer > 0 */
+ short time_sig_den ; /* any positive power of 2 > 0 */
+ int loop_mode ; /* see SF_LOOP enum */
+
+ int num_beats ; /* this is NOT the amount of quarter notes !!!*/
+ /* a full bar of 4/4 is 4 beats */
+ /* a full bar of 7/8 is 7 beats */
+
+ float bpm ; /* suggestion, as it can be calculated using other fields:*/
+ /* file's lenght, file's sampleRate and our time_sig_den*/
+ /* -> bpms are always the amount of _quarter notes_ per minute */
+
+ int root_key ; /* MIDI note, or -1 for None */
+ int future [6] ;
+ } SF_LOOP_INFO ;
+
++Example: +
++ SF_LOOP_INFO loop; + sf_command (sndfile, SFC_GET_LOOP_INFO, &loop, sizeof (loop)) ; ++
+Retrieve instrument information from file including MIDI base note, +keyboard mapping and looping informations(start/stop and mode). +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_INSTRUMENT + data : a pointer to an SF_INSTRUMENT struct + datasize : sizeof (SF_INSTRUMENT) ++ +
+The SF_INSTRUMENT struct is defined in <sndfile.h> as: +
+
+ enum
+ { /*
+ ** The loop mode field in SF_INSTRUMENT will be one of the following.
+ */
+ SF_LOOP_NONE = 800,
+ SF_LOOP_FORWARD,
+ SF_LOOP_BACKWARD,
+ SF_LOOP_ALTERNATING
+ } ;
+
+ typedef struct
+ { int gain ;
+ char basenote, detune ;
+ char velocity_lo, velocity_hi ;
+ char key_lo, key_hi ;
+ int loop_count ;
+
+ struct
+ { int mode ;
+ unsigned int start ;
+ unsigned int end ;
+ unsigned int count ;
+ } loops [16] ; /* make variable in a sensible way */
+ } SF_INSTRUMENT ;
+
+
++Example: +
++ SF_INSTRUMENT inst ; + sf_command (sndfile, SFC_GET_INSTRUMENT, &inst, sizeof (inst)) ; ++
+Set the instrument information for the file. +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_GET_INSTRUMENT + data : a pointer to an SF_INSTRUMENT struct + datasize : sizeof (SF_INSTRUMENT) ++
+Example: +
++ SF_INSTRUMENT inst ; + sf_command (sndfile, SFC_SET_INSTRUMENT, &inst, sizeof (inst)) ; ++
+Set the Variable Bite Rate encoding quality. +Currenly only implemented fro Ogg/Vorbis files. +
++Parameters: +
++ sndfile : A valid SNDFILE* pointer + cmd : SFC_SET_VBR_ENCODING_QUALITY + data : a pointer to double specifing VBR quality + datasize : sizeof (double) ++
+Example: +
++ double quality = 0.5 ; + sf_command (sndfile, SFC_SET_VBR_ENCODING_QUALITY, &quality, sizeof (double)) ; ++
+ The libsndfile home page is here :
+
+ http://www.mega-nerd.com/libsndfile/.
+
+Version : 1.0.25
+